1. Field of the Invention
The present invention relates to a fuel chamber provided in a fuel tank and preferably applied to an automotive vehicle.
2. Description of the Related Art
Conventionally, in an automotive vehicle with an electronic fuel injection apparatus, a fuel (generally a gasoline) in a fuel tank is supplied to the fuel injection apparatus by an electric fuel pump, a necessary amount of fuel is injected into a combustion chamber in an engine by the fuel injection apparatus, and an excessive fuel is returned to the fuel tank.
Accordingly, during an operation of the engine, a predetermined amount of fuel is always circulated between the fuel injection apparatus and the fuel tank, and only a necessary amount of fuel is injected to the combustion chamber of the engine among the circulated fuel.
In this case, since the fuel once returned to the engine (hereinafter, refer to a "return gasoline") becomes a significantly high temperature, a temperature of the whole gasoline within the tank is increased due to the heat of the return gasoline when the return gasoline is directly mixed into the fuel within the fuel tank, so that the gasoline is evaporated into a vapor.
Accordingly, there occur disadvantages that the gasoline increases an internal pressure of the tank, and the gasoline is wastefully consumed due to the evaporation.
Then, conventionally, a fuel chamber is provided within the fuel tank in such a manner that the gasoline within the tank can communicates, the gasoline within the fuel tank is introduced into the chamber, the gasoline within the chamber is supplied to the fuel injection apparatus by the fuel pump, and the return gasoline having a small amount of component having a high temperature but less vapor generation is returned within the chamber, so that the return gasoline having a high temperature is shut out from a fresh gasoline (having a low temperature) within the fuel tank, thereby preventing from a vaporization. Further, in order to reduce an unavailable remaining amount of the gasoline within the tank, it is performed that the fresh gasoline within the tank is sucked and introduced into the chamber by a liquid flow of the return gasoline.
However, when the fresh gasoline having a lot of vapor generating components within the tank is sucked and introduced into the chamber only by the liquid flow of the return gasoline, a temperature of the fresh gasoline is gradually increased, so that the vapor is generated from the fresh gasoline and a sufficient vapor prevention effect can not be always obtained.
Further, in accordance with a structure of the fuel chamber, there is a case that an unnecessary noise such as entrainment sound and the like is generated within the fuel chamber. In this case, an occupant feels the noise as an unpleasant sound, so that there has been a problem of injuring a quality feeling.
Still further, since the fuel chamber is disposed within the fuel tank of the automotive vehicle, a liquid surface of the fuel is changed at a time when the automotive vehicle turns, so that there have been problems that the fuel is not smoothly supplied to the fuel chamber, and that even when the fuel is once supplied into the fuel chamber, the fuel flows backward toward the fuel tank. The case, for example, that the fuel is not smoothly supplied to the fuel chamber will be described below on the basis of the substantially same structure as the structure disclosed in Japanese Patent Unexamined Laid-Open Publication No. 3-225060.
A structure of a conventional fuel chamber of this kind for an automotive vehicle is known, for example, as the structure shown in FIGS. 1 and 2.
In this structure, a fuel tank 1a made of a resin is provided in a fuel tank 1 for the vehicle, the fuel chamber 2 serving as a swirling tank fixed to a bottom portion 1b of a fuel tank main body 1 for storing a fuel.
The fuel chamber 2 is formed substantially in a box shape having a bottom and no top, and a communication opening 3 for communicating the fuel within the fuel tank 1 is formed in a peripheral wall portion 2b.
In the communication opening 3, in order to introduce the fuel within the fuel tank 1 into the fuel chamber main body 2a corresponding to the storage tank for the fuel, an inlet portion of a fuel passage 5 separated from the fuel chamber main body 2a is constituted by a partition wall 4 having a substantially L shape in a plan view and disposed along the peripheral wall portion 2b.
Further, an outlet portion of the fuel passage 5 is constituted by a feed-out port 6 disposed substantially in the opposite position with respect to the chamber main body 2a of the communication opening 3.
In the conventional fuel chamber structured in the above manner, even when the liquid surface of the fuel is inclined as shown in a two-dot chain line a in FIG. 2 at a time of turning or the like, a predetermined amount of remaining fuel corresponding to substantially half the fuel chamber main body 2a can be secured.
Then, since the feed-out port 6 is formed at the opposite position of the communication opening 3, the fuel is prevented from being flown out from the communication opening 3 by the partition wall 4 even when the liquid surface of the fuel is inclined as shown in a two-dot chain line bin FIG. 2. Therefore, amount of the fuel returning into the fuel tank main body 1a through the fuel passage 5 is a little, so that the predetermined amount of remaining fuel is substantially secured within the fuel chamber main body 2a.
Accordingly, since the predetermined amount of fuel can be substantially secured even when the liquid surface of the fuel is inclined to a different direction, a pump suction port 7 faced within the fuel chamber main body 2a is not exposed to an open air, so that the fuel can be efficiently sucked to a portion close to a terminal end.
In the conventional structure of the chamber, in order to increase the amount of the remaining fuel within the fuel chamber main body 2a, it is known that it is better to employ a structure for setting a predetermined amount of height d in such a manner as to make a position of the feed-out port 6 or a bottom surface 5a of the fuel passage 5 higher than a position of the bottom portion 2c of the fuel chamber main body 2a.
When the position of the feed-out port 6 or the bottom surface 5a of the fuel passage 5 is set to be higher than the position of the bottom portion 2c of the fuel chamber main body 2a, a lot of remaining fuel can be secured in comparison with the structure for securing the remaining fuel till a position shown in the two-dot chain line b mentioned above even when the liquid surface of the fuel is inclined as shown in a two-dot chain line c in FIG. 2 at a time of turning or the like.
However, when the position of the feed-out port 6 or the bottom surface 5a of the fuel passage 5 is set to be higher than the position of the bottom portion 2c of the fuel chamber main body 2a, there is a risk that the fuel within the fuel tank main body 1a can not flows over the bottom surface 5a of the fuel passage 5 or the feed-out port 6 at a time of reducing near the bottom portion 1b, thereby not being introduced into the chamber main body 2b.
Accordingly, even when the fuel is sucked out from the fuel chamber main body 2a, the fuel is remained within the fuel tank main body 1a, so that there is a problem that the fuel can not efficiently sucked out near the terminal end and, therefore, the fuel in the fuel tank main body 1a can not be supplied to the fuel chamber main body 2a.